1. Field of the Invention
The present invention relates to a relay device, an authentication server, and an authentication method.
2. Description of the Related Art
Conventionally, when a relay device is controlled by a provider, an authentication server has notified security information necessary for keeping data secret, securing data integrity, or the like to the relay device controlled by the provider (referred to as “provider-controlled relay device”, hereinafter). Accordingly, data has been kept secret and data integrity has been secured between a terminal device and the provider-controlled device. FIG. 1 shows that a secure communication path is established between a terminal device 100 and a provider-controlled relay device 200a. 
Additionally, it can be imagined that not only the provider-controlled relay device but also a relay device not controlled by the provider (referred to as provider-uncontrolled relay devices, hereinafter) will have to be accommodated (e.g., H. Yumida, et al, “IP-Based IMT Network Platform”, IEEE Personal Communication Magazine, October 2001, pp. 18 to 23). As the provider-uncontrolled relay device, for example, an access point set at user's home or office may be cited. Thus, in the case of accommodating such a provider-uncontrolled relay device, data must be kept secret and data integrity must be secured between the terminal device and the authentication server. FIG. 1 shows that a secure communication path is established among the terminal device 100, a provider-uncontrolled relay device 200b, and an authentication server 300.
However, the provider-uncontrolled relay device may disguise itself as a provider-controlled relay device by using an ID of the provider-controlled relay device to bug or falsify data, creating a danger of invading user's privacy. FIG. 2 shows that the provider-uncontrolled relay device 200b disguises itself as the provider-controlled relay device 200a by using an ID (ID#1) thereof.
The present invention has been developed with the foregoing problem in mind, and objects of the invention are to provide a relay device capable of preventing a danger that a provider-uncontrolled relay device will disguise itself as a provider-controlled relay device to bug or falsify data, thereby invading user's privacy, an authentication server, and an authentication method.